unlike the VAS and output stage trannies, Q7/8 does not swing voltage, it is constant current, i see no reason for concern....
ZTX450 for Q8 is more than plenty....Nelson Pass's favorite.....
for Q7, MPSA06 is more than enough even if you use a rail voltage higher than 60volts, you can even increase the value of R14 from 2k to 10k, the output impedance of the ring of two being around 200k is even helped by the higher value of R14...
btw, the usual caveat, be mindful of the pinouts...
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$40 minimum order
Amplabs has $40 minimum which is steep for 8 transistors. Are these substitutes also good for Q3,Q4?
Amplabs has $40 minimum which is steep for 8 transistors. Are these substitutes also good for Q3,Q4?
yes part ksc1845
my typing is almost as good as my ability to solder surface mount chips, yes part KSC1845. $2.04 for 10 of them plus $0.20 tariff shipped from Digikey. I live very close to Thief River Falls so should get tomorrow unless weather delays due to extreme cold (-26F, wind chill -50F)
my typing is almost as good as my ability to solder surface mount chips, yes part KSC1845. $2.04 for 10 of them plus $0.20 tariff shipped from Digikey. I live very close to Thief River Falls so should get tomorrow unless weather delays due to extreme cold (-26F, wind chill -50F)
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Can't start build
I finally got parts that had been backordered for a couple of months and was pretty exited to get started on construction. I'm greater than $700 invested if look at Deluxe 4 case, transformer, and parts I ordered. I had a whole weekend to work on it. Then, I found not a single resistor leg would fit. They should emphasize that the through hole openings are not just tight they are unnecessarily pinhole tight about 1/2 the width of a 1/4 watt dale resistor leg. Why are they so tight? There appears to be plenty of room for larger openings as the solder pads are very generous. Pretty sure I am not going to bother to finish this now as I am just too frustrated. I would like someone to add to parts list that one should order flimsy, cheap parts on purpose.
I finally got parts that had been backordered for a couple of months and was pretty exited to get started on construction. I'm greater than $700 invested if look at Deluxe 4 case, transformer, and parts I ordered. I had a whole weekend to work on it. Then, I found not a single resistor leg would fit. They should emphasize that the through hole openings are not just tight they are unnecessarily pinhole tight about 1/2 the width of a 1/4 watt dale resistor leg. Why are they so tight? There appears to be plenty of room for larger openings as the solder pads are very generous. Pretty sure I am not going to bother to finish this now as I am just too frustrated. I would like someone to add to parts list that one should order flimsy, cheap parts on purpose.
Looks like the resistor leads in the published BOM are all 0.44mm diameter whereas the Dale CMF55s (1/2 watt) are 0.64mm diameter. Assuming that's what you are using, though you said 1/4 watt. The 1/4 watt Dale CMF50s are 0.41mm lead diameter, so those would fit in theory.
Unless there's a manufacturing issue with the boards you received.
Unless there's a manufacturing issue with the boards you received.
Hey Jim! Argh. That sucks.
A few people over the years have had the same problem. The holes are exactly as specified by the gerber files we received from the designer, OSTripper. I will confirm the exact sizing on the PCB holes and post a note on the sales page and BOM.
As to how to resolve this for you...
The designer Pete (OSTripper) has been uncontactable for many years. However I have sent him an email just now to see if he responds. If I can get in touch with him, we can get the original design files and easily increase the size of the holes (we never received the design files from him, just the raw gerber files).
What I can suggest is that we produce a new batch of boards with increased hole size, and I send you a free replacement. This will take a few months, but if you are happy to wait I am happy to do this. I will try to get the original files from Pete, and if that isn't a viable option, I will have the holes in the original gerber files manually resized, and then make, ship, and stock the new batch, and send you a set.
What is the ideal new size for the resistor (and other) holes?
A few people over the years have had the same problem. The holes are exactly as specified by the gerber files we received from the designer, OSTripper. I will confirm the exact sizing on the PCB holes and post a note on the sales page and BOM.
As to how to resolve this for you...
The designer Pete (OSTripper) has been uncontactable for many years. However I have sent him an email just now to see if he responds. If I can get in touch with him, we can get the original design files and easily increase the size of the holes (we never received the design files from him, just the raw gerber files).
What I can suggest is that we produce a new batch of boards with increased hole size, and I send you a free replacement. This will take a few months, but if you are happy to wait I am happy to do this. I will try to get the original files from Pete, and if that isn't a viable option, I will have the holes in the original gerber files manually resized, and then make, ship, and stock the new batch, and send you a set.
What is the ideal new size for the resistor (and other) holes?
thankfully the pad circles are big enough so that you can still solder in resistors although i admit that is not ideal...
I have never seen anyone on this forum complains about the resistor holes size on any FirstWatt amp PCB.
Why the hole size cannot be made as same as all other amp boards.
I heard an very interest story already on another hifi forum that claims the hole size on The "Honey Badger" was purposefully made very tight. The leads can make contact with gold to avoid "the alloy sound" caused by the solder. That's why The "Honey Badger" sounds so beautifully.
Why the hole size cannot be made as same as all other amp boards.
I heard an very interest story already on another hifi forum that claims the hole size on The "Honey Badger" was purposefully made very tight. The leads can make contact with gold to avoid "the alloy sound" caused by the solder. That's why The "Honey Badger" sounds so beautifully.
Hi Guys, I have been tweaking my HB over the past few months and have managed to reduce the distortion considerably since my first measurement.
I recently found that increasing the ltp current to 6mA and then changing the LTP degeneration resistors to 120 ohms and changing C7 to 82pf and C8 to 390p to achieve the same unity gain crossover frequency FC. Doing so reduce my 2nd harmonic distortion from -80dB to -90dB and my 4th harmonic from -90dB to -95dB.
First picture is one of my first measurements.
Second is the measurement immediately before the 6mA change.
Last photo is after the 6mA change
I recently found that increasing the ltp current to 6mA and then changing the LTP degeneration resistors to 120 ohms and changing C7 to 82pf and C8 to 390p to achieve the same unity gain crossover frequency FC. Doing so reduce my 2nd harmonic distortion from -80dB to -90dB and my 4th harmonic from -90dB to -95dB.
First picture is one of my first measurements.
Second is the measurement immediately before the 6mA change.
Last photo is after the 6mA change
